1. Field of the Invention
This invention relates to devices for machining of materials. More specifically, this invention relates to polycrystalline diamond (PCD) and polycrystalline cubic boron nitride (PCBN) cutting tools, which for the purposes of this patent disclosure will both be commonly referred to as xe2x80x9cSuperabrasivesxe2x80x9d, and which are intended to be installed as the cutting element in drilling, milling, or turning operations on lathes, mills, or other metalworking, woodworking, machining, or shaping industrial equipment. Still more specifically, this invention relates to polycrystalline diamond or polycrystalline cubic boron nitride cutting tools, which have an integral chip-breaking feature.
2. Description of Related Art
Polycrystalline diamond and cubic boron nitride CBN cutting tools are used in industrial machinery, such as lathes, milling machines and other drilling and reaming applications, as well as general shaping of metals, wood, plastics, composites or other machinable materials. A number of different configurations, materials and geometries are used in polycrystalline diamond and PCBN cutting tool manufacture. Typically, diamond and CBN cutting tools that have chip-breaking features have the chip breaker feature added after the sintering processing step. Often the chip breaker is included in the cutting tool by use of an electric discharge grinding or machining which is a high temperature, cobalt depletive process. Laser etching processes or grinding steps of the final geometry may also be used. Such process steps can induce structural problems in the tool due to excessive heat and cobalt binder depletion as well as increasing the manufacturing time and cost because of the extra processing steps. These problems have restricted the production of PCD or PCBN chip-breaker tools by these known methods.
By way of introduction, a polycrystalline diamond cutter (PCD) or PCBN, or superabrasive polycrystalline cutting tool, is typically fabricated by placing a cemented tungsten carbide substrate into a refractory metal container (can) with a layer of diamond or cubic boron nitride crystal powder placed into the can adjacent to one face of the substrate. Additional cans are used to completely enclose the diamond powder and the carbide substrate. A number of such can assemblies are loaded into a high-pressure cell made from a low thermal conductivity extrudable material such as pyrophyllite or talc. The loaded high-pressure cell is then placed in a high-pressure press. The entire assembly is compressed under high pressure and temperature conditions. This causes the metal binder from the cemented carbide substrate to sweep from the substrate face through the diamond or CBN grains and to act as a reactive phase to promote the sintering of the diamond or CBN grains. The sintering of the diamond or CBN grains causes the formation of a polycrystalline diamond or CBN structure. As a result the diamond or CBN grains become mutually bonded to form a diamond or CBN mass over the substrate face. The metal binder may remain in the diamond or CBN layer within the pores of the polycrystalline structure or, alternatively, it may be removed via acid leaching and optionally replaced by another material forming so-called thermally Superabrasive tools. Variations of this general process exist and are described in the related art. This detail is provided so the reader may become familiar with the concept of sintering a diamond or CBN layer onto a substrate to form a Superabrasive cutting tool. For more information concerning this process, the reader is directed to U.S. Pat. No. 3,745,623, issued to Wentorf Jr. et al., on Jul. 7, 1973.
For general background material, the reader is directed to the following United States patents, each of which is hereby incorporated by reference in its entirety for the material contained therein.
U.S. Pat. No. 3,745,623 describes diamond tools and superpressure processes for the preparation thereof, where the diamond content is present either in form of a mass comprising diamond crystals bonded to each other or of a thin skin of diamond crystals bonded to each other.
U.S. Pat. No. 3,767,371 describes abrasive bodies comprising combinations of cubic boron nitride crystals and sintered carbide.
U.S. Pat. No. 4,403,015 describes a compound sintered compact for use in a cutting tool having particularly high properties in respect of bonded strength, hardness, wear resistance, plastic deformability and rigidity by bonding a diamond or cubic boron nitride containing a hard layer to a cemented carbide substrate with interposition of an intermediate bonding layer.
U.S. Pat. No. 4,387,287 describes a method for shaping polycrystalline, synthetic diamond and, in particular, to the production of profiled parts like tools.
U.S. Pat. No. 4,854,784 describes an improved metal cutting insert, which incorporates a polycrystalline diamond or a polycrystalline cubic boron nitride material therein as a cutting edge material.
U.S. Pat. No. 5,011,514 describes superabrasive cutting elements, backed compacts and methods for their manufacture, wherein metal coated superabrasive particles are cemented under high pressure/high temperature conditions.
U.S. Pat. No. 5,026,960 describes an oversize compact blank having a surface and edges that establish it as oversized. A chip breaker pattern is formed on the compact blank surface.
U.S. Pat. No. 5,193,948 describes an insert having a cutting segment of a polycrystalline diamond or cubic boron wafered between two layers of a hard metal carbide is bonded into a pocket in a standard insert and machined to form a chip breaker having a clearance surface and expose the cutting edge of polycrystalline material integral with the cutting segment.
U.S. Pat. No. 5,405,711 describes an indexable cutting insert having a polycrystalline cutting edge along the entire periphery of the insert.
U.S. Pat. No. 5,447,208 describes a superhard cutting element having a polished, low friction, substantially planar cutting face with a surface finish roughness of 10 micro inches and preferably 0.5 micro inches or less.
U.S. Pat. No. 5,449,048 describes a drag bit having a plurality of blades or ribs on its end face that has one or more pockets milled into the top surfaces of said blades using a ball-nosed end mill to create a plurality of pockets, each having a spherical or a semi-spherical first end and a second end having a semicircular configuration that intersects with the leading edge face of the rib.
U.S. Pat. No. 5,569,000 describes a cutting insert that is formed by making a body, which includes a chip face having an outer peripheral edge.
U.S. Pat. No. 5,653,300 describes a superhard cutting element having a polished, low friction substantially planar cutting face with a surface finish roughness of 10 micro inches or less and preferably 0.5 micro inches or less.
U.S. Pat. No. 5,704,735 describes a fly cutter wheel which has at least one projecting tooth at a distance from its rotation axis and a chip breaker forward of said tooth in its rotation direction.
U.S. Pat. No. 5,709,907 describes a method of producing a cutting tool, comprising a substrate which has a roughened surface that presents a surface roughness of between 10 micro inches and 125 micro inches.
U.S. Pat. No. 5,722,803 describes a coated cutting tool and a method of producing the same.
U.S. Pat. No. 5,771,972 describes a mill assembly and whipstock assembly.
In cutting tools, which are used to machine metals, composites, wood or other machinable materials, it is often desirable to provide a tool having a chip breaker feature. More particularly, it is desirable to provide a method for forming such a chip breaker tool feature by coining a desired geometry onto a polycrystalline diamond or PCBN surface prior to or during high temperature and high-pressure sintering.
Therefore, it is an object of this invention to provide a Superabrasive cutting tool with an integral chip breaker feature.
It is a further object of this invention to provide a method of manufacturing a Superabrasive cutting tool with a chip breaker feature by coining the desired chip-breaker geometry onto the diamond or CBN surface prior to high temperature/high pressure pressing.
It is a further object of this invention to provide a method of manufacturing a Superabrasive cutting tool with a chip breaker feature by forming the chip breaker geometry in-situ during high temperature/high pressure sintering.
It is another object of this invention to provide a method of manufacturing a Superabrasive cutting tool with a chip-breaker feature by inclusion of a rigid or semi-rigid form against the diamond or CBN in the high temperature/high pressure cell during sintering.
It is a further object of this invention to provide a method of manufacturing a Superabrasive cutting tool with a chip breaker feature that avoids the application of heat, or the removal of cobalt by EDM or EDG or laser processes.
It is a further object of this invention to provide a method of manufacturing a Superabrasive cutting tool with a chip breaker feature that avoids the grinding of the final surface geometry.
These and other objectives, features and advantages of this invention, which will be readily apparent to those of ordinary skill in the art upon review of the following drawings, specification, and claims, are achieved by the invention as described in this application.